Radiator for power semiconductor and assembling method thereof

Abstract

The invention belongs to the technical field of radiators, and particularly relates to a radiator for a power semiconductor and an assembling method thereof. The radiator comprises a heat dissipation bottom plate, a heat dissipation plate and a heat dissipation shell, the heat dissipation bottom plate is used for connecting the power semiconductor device and the heat dissipation plate, the heat dissipation bottom plate and the heat dissipation plate form a heat dissipation bottom plate-heat dissipation plate combination body through a vacuum brazing or pressure sintering process, and the heat dissipation bottom plate-heat dissipation plate combination body is reliably connected with the heat dissipation shell; the heat dissipation bottom plate is made of a material with a thermal expansion coefficient similar to that of the power semiconductor device; a window is arranged on the heat dissipation bottom plate, a protruding part is arranged at the position, corresponding to the window, of the heat dissipation plate, and the protruding part of the heat dissipation plate penetrates through the window to make contact with the power semiconductor device. According to the radiator, the titanium alloy or the tungsten copper alloy with the thermal expansion coefficient similar to that of the power semiconductor device is adopted as the heat dissipation bottom plate, and the protruding parts on the heat dissipation plate penetrate through the windows of the heat dissipation bottom plate to be in direct contact with the power semiconductor device, so that the heat dissipation efficiency can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of power semiconductor radiators, and particularly relates to a radiator for power semiconductors and an assembly method thereof. Background Art

[0002] With the wide use of third-generation semiconductor power devices, the power density of power semiconductor devices has been continuously increasing, and the heat flux density has been continuously rising. The heat dissipation technology has become the biggest obstacle hindering the development of high-performance power semiconductors. To ensure the performance and reliability of high-power semiconductor devices, a more efficient heat dissipation technology is needed to reduce the junction temperature of power devices and the radiator and the reliability of the bonding surface.

[0003] Current technologies mostly select alloys with a high heat dissipation rate. For example, in patent CN114464583B, a copper alloy is used as the main heat dissipation material. However, the copper alloy has a high density, making it difficult to control the weight of the radiator made of copper alloy. When applied to new energy vehicle inverters, it brings additional energy consumption. Moreover, the copper alloy is easily corroded in the coolant, affecting the life and reliability of the radiator, and adding a coating leads to an increase in the cost of the radiator.

[0004] Another solution adopts a specially designed internal structure. For example, in patent CN117098365A, different pin-fin structures are designed to improve the heat dissipation efficiency of the radiator, and screws are used to fix the pin-fin plate and the heat dissipation housing. This technology ignores the reliability of the bonding surface between the power semiconductor device and the radiator. During actual use, as the junction temperature between the device and the radiator continuously rises, due to the mismatch of the thermal expansion coefficients of the heat dissipation plate and the housing, the connection surface between the device and the radiator breaks, exacerbating the increase in the junction temperature and ultimately leading to device failure. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies existing in the prior art and provide a radiator for power semiconductors and an assembly method thereof. In the radiator of the present invention, a titanium alloy or tungsten copper alloy with a thermal expansion coefficient similar to that of the power semiconductor device is used as the heat dissipation bottom plate. Different openings are designed on the heat dissipation bottom plate, and different protrusions are designed on the heat dissipation plate. The protrusions pass through the windows of the heat dissipation bottom plate and directly contact the power semiconductor device to improve the heat dissipation efficiency. At the same time, the heat dissipation bottom plate is roughened to improve the thermal conductivity of the heat dissipation bottom plate and the reliability of brazing between the heat dissipation bottom plate and the heat dissipation plate.

[0006] To achieve the above technical objectives, the technical solutions adopted in the embodiments of the present invention are as follows:

[0007] In a first aspect, an embodiment of the present invention provides a heat sink for a power semiconductor, including a heat dissipation bottom plate, a heat dissipation plate, and a heat dissipation housing. The heat dissipation bottom plate is used to connect a power semiconductor device and the heat dissipation plate. The heat dissipation bottom plate and the heat dissipation plate form a heat dissipation bottom plate - heat dissipation plate combination through a vacuum brazing or pressure sintering process. The heat dissipation bottom plate - heat dissipation plate combination is reliably connected to the heat dissipation housing through a brazing or friction stir welding process;

[0008] The heat dissipation bottom plate is made of a material with a thermal expansion coefficient similar to that of the power semiconductor device, and its thickness ≤ 1 mm;

[0009] Windows are provided on the heat dissipation bottom plate, and a convex portion is provided on the heat dissipation plate at a position corresponding to the windows. The convex portion of the heat dissipation plate passes through the windows and contacts the power semiconductor device.

[0010] Further, the heat dissipation bottom plate is made of titanium alloy or tungsten copper alloy.

[0011] Further, the heat dissipation plate is made of an aluminum alloy material, and a heat dissipation matrix is formed on the heat dissipation plate by forging or mechanical cutting. The heat dissipation matrix includes pin - fin and / or wave - fin.

[0012] Further, the heat dissipation housing is a container for containing a coolant, and is provided with an inlet and an outlet connected to the host system;

[0013] The heat dissipation housing is made of an aluminum alloy material, and the interior of the heat dissipation housing and the heat dissipation matrix are subjected to corresponding anti - corrosion treatment according to the selected coolant.

[0014] Further, a groove is provided at the joint part of the heat dissipation bottom plate combined with the heat dissipation plate, and the depth of the groove is 5 - 20 μm.

[0015] Further, the window is opened at the center position of the heat dissipation bottom plate, and the window opening ratio is 0.5% - 10%.

[0016] In a second aspect, an embodiment of the present invention provides an assembly method for the heat sink for a power semiconductor described in the first aspect, including the following steps:

[0017] Step S1: Select a titanium alloy or tungsten copper alloy plate as the heat dissipation bottom plate according to the heat dissipation requirements of the power semiconductor device, and open windows on the heat dissipation bottom plate to form a plurality of windows;

[0018] Step S2: Etch the surface of the heat dissipation bottom plate with windows opened to form a groove with a depth of 5 - 20 μm, and use a mixed solution of nitric acid, hydrofluoric acid, and water to remove the oil stains and their oxides on the surface of the heat dissipation bottom plate.

[0019] Step S3: Design the convex part of the heat sink plate according to the window specifications of the heat dissipation base plate to fit the window of the heat dissipation base plate, and use acetone to remove the oil and oxides on the surface of the heat sink plate;

[0020] Step S4: Press the heat dissipation base plate, the solder, and the heat sink plate together in sequence, place them in a vacuum brazing machine, evacuate the air in the cavity, and keep them at 400 - 600 °C for 3 - 20 minutes. Wait until a good brazed joint is formed between the heat dissipation base plate and the heat sink plate, and then cool down to room temperature to obtain a heat dissipation base plate - heat sink plate combination;

[0021] Step S5: Place the heat dissipation base plate - heat sink plate combination formed in Step S4 in a forging press, and forge a heat dissipation matrix on the heat sink plate at 100 - 300 °C. After forging, trim and shape it through CNC;

[0022] Step S6: Process and form a heat dissipation housing by means of CNC machining;

[0023] Step S7: Electroplate an anticorrosive layer with a thickness of 0.1 - 5 μm on the surface of the heat dissipation matrix trimmed and shaped in Step S5 and the inside of the heat dissipation housing in Step S6;

[0024] Step S8: Place the heat dissipation base plate - heat sink plate combination with the anticorrosive layer and the heat dissipation housing in a friction stir welding machine, control the speed of the stirring head and the moving speed of the workpiece, and weld the heat dissipation base plate - heat sink plate combination and the heat dissipation housing together;

[0025] Step S9: Anneal the welded workpiece in an oven at 200 - 300 °C to eliminate the stress generated during the workpiece processing. After annealing, obtain the finished radiator.

[0026] Further, in Step S4, a foil - shaped Al - Si - Mg alloy film is used as the solder for bonding the heat dissipation base plate and the heat sink plate. The thickness of the foil - shaped Al - Si - Mg alloy film is 10 - 300 μm, where the weight percentage of Si is 5 - 20%, the weight percentage of Mg is 0.5 - 5%, and the balance is Al.

[0027] Further, in Step S3, the size of the convex part is less than or equal to the size of the window.

[0028] Further, in Step S8, when the heat dissipation base plate - heat sink plate combination and the heat dissipation housing are welded, the heat dissipation matrix on the heat sink plate is located inside the heat dissipation housing.

[0029] The beneficial effects brought by the technical solution provided by the embodiment of the present invention are:

[0030] (1) Aiming at the problem of the mismatch between the thermal expansion coefficients of the heat dissipation plate and the power semiconductor device, the present invention adds an alloy material with a low thermal expansion coefficient (such as titanium alloy or tungsten copper alloy) as the heat dissipation bottom plate in the radiator. The thermal expansion coefficients of titanium alloy or tungsten copper alloy are close to those of the power semiconductor device, thereby improving the connection stability between the power semiconductor device and the heat dissipation bottom plate, avoiding the fracture of the joint caused by the large difference in thermal expansion coefficients, and further affecting the performance and reliability of the semiconductor device, thus reducing the problem of inconsistent thermal expansion coefficients at the joint surface between the power device and the radiator.

[0031] (2) Aiming at the specific heat dissipation requirements of the power semiconductor device, different openings are designed on the heat dissipation bottom plate to avoid insufficient heat dissipation caused by using titanium alloy or tungsten copper alloy with a lower thermal conductivity.

[0032] (3) Aiming at the problem of the low thermal conductivity of titanium alloy or tungsten copper alloy, according to the actual connection dimensions of the power semiconductor device, different protrusions are designed on the heat dissipation plate. The protrusions pass through the windows of the heat dissipation bottom plate and directly contact the power semiconductor device to improve the heat dissipation efficiency. At the same time, the heat dissipation bottom plate is roughened. By using methods such as mechanical stamping, chemical etching or laser etching, grooves are formed on the surface of the heat dissipation bottom plate that is joined to the heat dissipation plate to improve the thermal conductivity of the titanium alloy or tungsten copper alloy heat dissipation bottom plate and the reliability of the brazing between the heat dissipation bottom plate and the heat dissipation plate.

[0033] (4) Aiming at the liquid leakage problem caused by thermal stress during the use of the heat dissipation plate and the heat dissipation housing, the present invention uses a brazing or friction stir welding process to form a stable alloy layer between the heat dissipation plate and the heat dissipation bottom plate to make a heat dissipation bottom plate - heat dissipation plate combination to improve the stability of the radiator.

[0034] (5) The heat dissipation plate of the present invention not only adopts an efficient heat dissipation matrix, but also provides support for the heat dissipation bottom plate. Furthermore, a thinner titanium alloy or tungsten copper alloy can be selected, reducing the weight of the radiator and improving the economy of the radiator.

[0035] (6) The heat dissipation plate and the heat dissipation housing use the same aluminum alloy material, improving the reliability of the welded joint, avoiding the voids and cracks that are prone to occur during the welding of different alloys, and avoiding the possibility of liquid leakage during the later use process. Description of the Drawings

[0036] Figure 1 It is a schematic structural diagram of the heat dissipation bottom plate in the embodiment of the present invention.

[0037] Figure 2 is Figure 1 A schematic structural diagram of the heat dissipation bottom plate etched with V-shaped grooves in

[0038] Figure 3Schematic diagram of the structure of the heat dissipation plate in the embodiment of the present invention.

[0039] Figure 4 Schematic diagram of the structure of the welded heat dissipation bottom plate and heat dissipation plate in the embodiment of the present invention.

[0040] Figure 5 Schematic diagram of the structure of the combination of the heat dissipation bottom plate with a heat dissipation matrix and the heat dissipation plate in the embodiment of the present invention.

[0041] Figure 6 Schematic diagram of the structure of the heat dissipation housing in the embodiment of the present invention.

[0042] Figure 7 Schematic diagram of the assembly structure of the heat dissipation bottom plate - heat dissipation plate combination and the heat dissipation housing in the embodiment of the present invention.

[0043] Figure 8 For Figure 7 Schematic diagram of the structure during welding of the assembly structure in

[0044] Figure 9 Schematic diagram of the exploded structure of the heat sink for power semiconductors in the embodiment of the present invention.

[0045] Figure 10 Schematic diagram of the structure of the first type of groove on the heat dissipation bottom plate in the embodiment of the present invention.

[0046] Figure 11 Schematic diagram of the structure of the second type of groove on the heat dissipation bottom plate in the embodiment of the present invention.

[0047] Figure 12 Schematic diagram of the structure of the third type of groove on the heat dissipation bottom plate in the embodiment of the present invention.

[0048] Explanation of reference numerals: 1 - heat dissipation bottom plate; 2 - heat dissipation plate; 3 - heat dissipation housing; 4 - window; 5 - protrusion; 6 - heat dissipation matrix; 7 - groove; 8 - solder. Detailed implementation manners

[0049] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by orientation words such as "inside, outside", "above, below", "left, right", etc. is usually based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description. Without contrary explanations, these orientation words do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the protection scope of the present invention.

[0050] A heat sink for a power semiconductor includes a heat dissipation base plate 1, a heat dissipation plate 2, and a heat dissipation housing 3. The heat dissipation base plate 1 is used to connect the power semiconductor device and the heat dissipation plate 2. The heat dissipation base plate 1 and the heat dissipation plate 2 form a combined body through a vacuum brazing or pressure sintering process, and the combined body is reliably connected to the heat dissipation housing 3 through a brazing or friction stir welding process;

[0051] The heat dissipation base plate 1 is made of a material with a thermal expansion coefficient similar to that of the power semiconductor device, and the thickness is ≤ 1 mm;

[0052] A window 4 is provided on the heat dissipation base plate 1, and a protruding portion 5 is provided on the heat dissipation plate 2 at a position corresponding to the window 4. The protruding portion 5 of the heat dissipation plate 2 passes through the window 4 and contacts the power semiconductor device.

[0053] The heat dissipation base plate 1 is made of a titanium alloy (by mass fraction, including the following components: Al 3 - 8%, V 3 - 6%, and the balance is Ti) or a tungsten copper alloy (by mass fraction, including the following components: W 60 - 90%, copper 10 - 40%);

[0054] The heat dissipation plate 2 is made of an aluminum alloy material. A heat dissipation matrix 6 is formed on the heat dissipation plate 2 by forging or mechanical cutting. The heat dissipation matrix 6 includes pin - fin and / or wave - fin.

[0055] The heat dissipation housing 3 is a container for the coolant, and is provided with an inlet and an outlet connected to the host system;

[0056] The heat dissipation housing 3 is made of an aluminum alloy material. The interior of the heat dissipation housing 3 and the heat dissipation matrix 6 are subjected to corresponding anti - corrosion treatments according to the selected coolant. Among them, for the aluminum alloy of the heat dissipation plate 2 and the heat dissipation housing 3, by mass fraction, the aluminum alloy includes the following components: Mg 0.2 - 2.0%, Si 0.2 - 1.0%, and the balance is Al.

[0057] A groove 7 is provided at the joint part of the heat dissipation base plate 1 that is combined with the heat dissipation plate 2. The depth of the groove 7 is 5 - 20 μm. The groove 7 is a V - shaped groove (as shown in Figure 10 ), a square groove (as shown in Figure 12 ), or an arc - shaped groove (as shown in Figure 11 ), and preferably a V - shaped groove.

[0058] The window 4 is opened at the center position of the heat dissipation base plate 1, and the window opening ratio is 0.5% - 10%. The window opening ratio is the ratio of the area of the window 4 to the area of the heat dissipation base plate 1.

[0059] When the heat dissipation base plate 1 is made of titanium alloy and the heat dissipation plate 2 is made of aluminum alloy, the thermal conductivity between the heat dissipation base plate and the heat dissipation plate under different window opening ratios is shown in Table 1. Note that in order to avoid additional processing processes, only the heat dissipation base plate was windowed during the thermal conductivity test in Table 1. A foil-shaped Al-Si-Mg alloy thin film was selected as the solder (by weight fraction, including 85% Al, 13% Si, and 2% Mg), and the heat dissipation base plate and the heat dissipation plate were welded together by vacuum brazing. The welding temperature was 500 °C and the holding time was 10 minutes.

[0060] Table 1 Thermal conductivity between titanium alloy heat dissipation base plate and aluminum alloy heat dissipation plate under different window opening ratios

[0061] Comparison Items Heat Dissipation Base Plate Heat Dissipation Plate Window Opening Ratio (%) Thermal Conductivity W / (m·K) Comparative Example 1 Titanium Alloy Aluminum Alloy None 10.5 Example 1 Titanium Alloy Aluminum Alloy 0.5 23.6 Example 2 Titanium Alloy Aluminum Alloy 1 47.1 Example 3 Titanium Alloy Aluminum Alloy 5 63.9 Example 4 Titanium Alloy Aluminum Alloy 10 83.7 Example 5 Titanium Alloy Aluminum Alloy 20 91.2 Example 6 Tungsten Copper Alloy Aluminum Alloy 10 97.5

[0062] Note that in order to control a single variable in Table 1, the titanium alloy used to make the heat dissipation base plate in Examples 1-5 and Comparative Example 1 is the same composition of titanium alloy, and the aluminum alloy used to make the heat dissipation plate in Examples 1-6 and Comparative Example 1 is the same composition of aluminum alloy.

[0063] It can be seen from Table 1 that as the window opening ratio increases, the thermal conductivity also increases accordingly. However, if the window opening ratio is too high, cracking of the titanium alloy or tungsten copper alloy outer frame will occur due to the inconsistent coefficient of thermal expansion, affecting the bonding quality between the device and the heat dissipation base plate. When the window opening ratio exceeds 10%, the outer frame strength decreases significantly. Therefore, the preferred window opening ratio is 0.5%-10%. Although tungsten copper alloy has a higher thermal conductivity at the same window opening ratio, due to the high processing difficulty and cost of tungsten copper alloy, titanium alloy is preferably used as the heat dissipation plate material.

[0064] To avoid the influence of windowing operation on the heat dissipation base plate and the heat dissipation plate, the influence of different etching methods and etching depths on the heat dissipation capacity was studied separately under the condition of no windowing. When the heat dissipation base plate 1 is made of titanium alloy and tungsten copper alloy plate, and the heat dissipation plate 2 is made of aluminum alloy plate, the influence of different etching methods on the joint part of the heat dissipation base plate - heat dissipation plate combination and different etching depths on the thermal conductivity is shown in Table 2. At this time, a foil-shaped Al-Si-Mg alloy thin film was selected as the solder (by weight fraction, including 85% Al, 13% Si, and 2% Mg), and the heat dissipation base plate and the heat dissipation plate were welded together by vacuum brazing. The welding temperature was 500 °C and the holding time was 10 minutes.

[0065] Table 2 Influence of etching methods and etching depths on the thermal conductivity of the heat dissipation base plate and the heat dissipation plate combination

[0066] Comparison Items Heat Dissipation Base Plate Heat Dissipation Plate Etching Method Etching Depth (μm) Thermal Conductivity W / (m·K) Comparative Example 2 Titanium Alloy Aluminum Alloy None None 10.5 Example 7 Titanium Alloy Aluminum Alloy Mechanical Stamping 5 13.7 Example 8 Titanium Alloy Aluminum Alloy Chemical Etching 5 15.1 Example 9 Titanium Alloy Aluminum Alloy Laser Etching 5 17.6 Example 10 Titanium Alloy Aluminum Alloy Laser Etching 1 16.9 Example 11 Titanium Alloy Aluminum Alloy Laser Etching 20 25.3 Example 12 Titanium Alloy Aluminum Alloy Laser Etching 50 18.5 Example 13 Tungsten Copper Alloy Aluminum Alloy Laser Etching 5 37.4

[0067] Note that in Table 2, to control a single variable, the titanium alloy used to make the heat dissipation base plate in Examples 7-12 and Comparative Example 2 is a titanium alloy with the same composition, and the aluminum alloy used to make the heat dissipation plate in Examples 7-13 and Comparative Example 2 is an aluminum alloy with the same composition.

[0068] As can be seen from Table 2, etching the heat dissipation base plate and the heat dissipation plate combination to different depths using different etching methods will increase its thermal conductivity. When the etching depth is 5 μm, the thermal conductivity of the combination is the highest when laser etching is used. When different etching depths are formed by laser etching at the same time, as the etching depth increases, the thermal conductivity shows a trend of first increasing and then decreasing, and the preferred etching depth is 1-20 μm.

[0069] As an implementation method, an assembly method for a power semiconductor radiator includes the following steps:

[0070] Step S1: Select a titanium alloy (by mass fraction, the titanium alloy includes the following components: Al 3-8%, V 3-6%, and the balance is Ti) as the heat dissipation base plate 1 according to the heat dissipation requirements of the power semiconductor device, with a thickness of 400 μm, and open windows on the heat dissipation base plate 1 to form a number of windows 4, and the window opening ratio is 10%, as Figure 1 shown;

[0071] Step S2: Use the laser etching method to etch a V-shaped groove with a depth of 5 μm on the surface of the heat dissipation base plate 1, and use a mixed solution of nitric acid, hydrofluoric acid and water to remove the oil and its oxides on the surface of the heat dissipation base plate 1, as Figure 2 shown;

[0072] Step S3: Design the protrusion 5 of the heat dissipation plate 2 according to the window opening specifications of the heat dissipation base plate 1 to fit the window 4 of the heat dissipation base plate 1, and use acetone to remove the oil and oxides on the surface of the heat dissipation plate 2, as Figure 3 shown;

[0073] The heat dissipation plate 2 is made of an aluminum alloy (by mass fraction, the aluminum alloy includes the following components: Mg 0.2-2.0%, Si 0.2-1.0%, and the balance is Al);

[0074] Step S4: Use a foil-shaped Al-Si-Mg alloy film as the solder for forming the combination of the heat dissipation base plate 1 and the heat dissipation plate 2, press the heat dissipation base plate 1, the solder and the heat dissipation plate 2 together, place them in a vacuum brazing machine, evacuate the air in the cavity, and keep it at 500 °C for 10 minutes. Wait until a good brazed joint is formed between the heat dissipation base plate 1 and the heat dissipation plate 2, and cool it to room temperature to obtain a heat dissipation base plate-heat dissipation plate combination, as Figure 4 shown;

[0075] The thickness of the foil-shaped Al-Si-Mg alloy film is 200 μm, where the weight percentage of Si is 13%, the weight percentage of Mg is 2%, and the balance is Al.

[0076] Step S5: Place the welded heat dissipation base plate - heat dissipation plate assembly in a forging press. At 200 °C, forge heat dissipation matrices 6 on the heat dissipation plate 2. The heat dissipation matrices 6 are composed of multiple pin-fin heat dissipation fins. After forging, trim and shape them through CNC, as Figure 5 shown;

[0077] Step S6: Process and form the heat dissipation housing 3 through CNC machining, as Figure 6 shown;

[0078] Step S7: Electroplate a nickel anti-corrosion layer with a thickness of 3 μm on the heat dissipation base plate - heat dissipation plate assembly trimmed and formed in Step S5 and the heat dissipation housing 3 in Step S6;

[0079] Step S8: Place the heat dissipation base plate - heat dissipation plate assembly with the anti-corrosion layer and the heat dissipation housing 3 in a friction stir welding machine. Control the speed of the stirring head and the moving speed of the workpiece, and weld the heat dissipation base plate - heat dissipation plate assembly and the heat dissipation housing 3 together, as Figure 7 and 8 shown;

[0080] Step S9: Anneal the welded workpiece in an oven at 250 °C to eliminate the stress generated during the workpiece processing. After annealing, obtain the finished radiator, as Figure 9 shown.

[0081] In this embodiment, the measured value of the thermal conductivity of the finally manufactured radiator is 82.6 W / (m·K), and no problems such as cracking or delamination of the welding surface of the power device are found in actual applications.

[0082] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A heat sink for a power semiconductor, characterized in that: The invention comprises a heat dissipation base plate (1), a heat dissipation plate (2) and a heat dissipation shell (3), wherein the heat dissipation base plate (1) is used to connect a power semiconductor device and the heat dissipation plate (2), the heat dissipation base plate (1) and the heat dissipation plate (2) are formed into a heat dissipation base plate-heat dissipation plate combination by vacuum brazing or pressure sintering process, and the heat dissipation base plate-heat dissipation plate combination and the heat dissipation shell (3) are reliably connected by brazing or friction stir welding process; The heat dissipation base plate (1) is made of a material having a thermal expansion coefficient close to that of the power semiconductor device. A window (4) is arranged on the heat dissipation base plate (1). A protrusion (5) is arranged on the heat dissipation plate (2) at a position corresponding to the window (4). The protrusion (5) of the heat dissipation plate (2) passes through the window (4) and contacts the power semiconductor device.

2. The heat sink for power semiconductor according to claim 1, characterized in that: The heat dissipation base plate (1) is made of titanium alloy or tungsten-copper alloy and has a thickness of ≤1 mm.

3. The heat sink for power semiconductor according to claim 1, characterized in that: The heat dissipation plate (2) is made of an aluminum alloy material, and a heat dissipation matrix (6) is formed on the heat dissipation plate (2) by forging or mechanical cutting, and the heat dissipation matrix (6) includes pin-fins and / or wave-fins.

4. The heat sink for power semiconductor according to claim 1, characterized in that: The heat dissipation housing (3) is a container for containing coolant and is provided with a water inlet and a water outlet connected to the host system; The heat dissipation housing (3) is made of an aluminum alloy material, and the interior of the heat dissipation housing (3) and the surface of the heat dissipation matrix (6) are subjected to corresponding anti-corrosion treatment according to the selected coolant.

5. The heat sink for power semiconductor according to claim 1, characterized in that: A joint portion of the heat dissipation base plate (1) that is combined with the heat dissipation plate (2) is provided with a groove (7), and the depth of the groove (7) is 5-20 μm.

6. The heat sink for power semiconductor according to claim 1, characterized in that: The window (4) is opened at the center of the heat dissipation base plate (1), and the window opening ratio is 0.5%-10%.

7. The method for assembling a heat sink for a power semiconductor according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step S1, selecting a titanium alloy or tungsten copper alloy plate as a heat dissipation base plate (1) according to the heat dissipation requirements of the power semiconductor device, and opening windows (4) on the heat dissipation base plate (1); Step S2, etching the surface of the heat dissipation base plate (1) after the window is opened to form a groove (7) with a depth of 5-20 μm, and using a mixture of nitric acid, hydrofluoric acid and water to remove oil stains and oxides on the surface of the heat dissipation base plate (1); Step S3, designing the raised portion (5) of the heat sink (2) according to the window opening specifications of the heat sink base (1) to fit the window (4) of the heat sink base (1), and using acetone to remove oil stains and oxides on the surface of the heat sink (2); Step S4, sequentially pressing the heat dissipation base plate (1), the brazing material and the heat dissipation plate (2) together, placing them in a vacuum brazing machine, exhausting the air in the cavity, keeping the temperature at 400-600° C. for 3-20 minutes, and waiting for the heat dissipation base plate (1) and the heat dissipation plate (2) to form a good brazing joint, cooling the temperature to room temperature, and obtaining a heat dissipation base plate-heat dissipation plate combination; Step S5, placing the heat dissipation base plate-heat dissipation plate combination formed in step S4 in a forging machine, forging a heat dissipation matrix (6) on the heat dissipation plate (2) at 100-300° C., and trimming and shaping the heat dissipation matrix (6) by CNC after forging; Step S6, forming a heat dissipation housing (3) by CNC machining; Step S7, electroplating a corrosion-resistant layer with a thickness of 0.1-5 μm on the surface of the heat dissipation matrix (6) trimmed and formed in step S5 and the interior of the heat dissipation housing (3) in step S6; Step S8, placing the heat dissipation base plate-heat dissipation plate combination and the heat dissipation shell (3) forming the anti-corrosion layer in a friction stir welding machine, controlling the speed of the stirring head and the moving speed of the workpiece, and welding the heat dissipation base plate-heat dissipation plate combination and the heat dissipation shell (3) together; Step S9, placing the welded workpiece in an oven at 200-300° C. for annealing to eliminate stress generated during the workpiece processing. After annealing, a finished heat sink is obtained.

8. The method for assembling a heat sink for a power semiconductor according to claim 7, characterized in that: In step S4, a foil-like Al-Si-Mg alloy film is used as a solder for bonding the heat dissipation base plate (1) and the heat dissipation plate (2), wherein the foil-like Al-Si-Mg alloy film has a thickness of 10-300 μm, wherein the weight percentage of Si is 5-20%, the weight percentage of Mg is 0.5-5%, and the balance is Al.

9. The method for assembling a heat sink for a power semiconductor according to claim 7, characterized in that: In step S3, the size of the protrusion (5) is smaller than or equal to the size of the window (4).

10. The method for assembling a heat sink for a power semiconductor according to claim 7, characterized in that: In step S8, when the heat dissipation base plate-heat dissipation plate combination and the heat dissipation shell (3) are welded, the heat dissipation matrix (6) on the heat dissipation plate (2) is located inside the heat dissipation shell (3).

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